Re: [PATCH v2] rust: bug: Add bug macro

Hi FUJITA,

kernel test robot noticed the following build errors:

[auto build test ERROR on dc59e4fea9d83f03bad6bddf3fa2e52491777482]

url:    https://github.com/intel-lab-lkp/linux/commits/FUJITA-Tomonori/rust-bug-Add-bug-macro/20260709-080347
base:   dc59e4fea9d83f03bad6bddf3fa2e52491777482
patch link:    https://lore.kernel.org/r/20260709000103.2912159-1-tomo%40aliasing.net
patch subject: [PATCH v2] rust: bug: Add bug macro
config: um-allmodconfig (https://download.01.org/0day-ci/archive/20260709/[email protected]/config)
compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
rustc: rustc 1.96.0 (ac68faa20 2026-05-25)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260709/[email protected]/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All errors (new ones prefixed by >>):

   In file included from kernel/sched/rq-offsets.c:5:
   In file included from kernel/sched/sched.h:28:
   In file included from include/linux/cgroup_api.h:1:
   In file included from include/linux/cgroup.h:27:
   In file included from include/linux/kernel_stat.h:8:
   In file included from include/linux/interrupt.h:11:
   In file included from include/linux/hardirq.h:11:
   In file included from arch/um/include/asm/hardirq.h:24:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:12:
   In file included from arch/um/include/asm/io.h:24:
   include/asm-generic/io.h:1209:55: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
   1209 |         return (port > MMIO_UPPER_LIMIT) ? NULL : PCI_IOBASE + port;
   |                                                   ~~~~~~~~~~ ^
   1 warning generated.
   In file included from rust/helpers/helpers.c:49:
   In file included from rust/helpers/blk.c:3:
   In file included from include/linux/blk-mq.h:5:
   In file included from include/linux/blkdev.h:9:
   In file included from include/linux/blk_types.h:10:
   In file included from include/linux/bvec.h:10:
   In file included from include/linux/highmem.h:12:
   In file included from include/linux/hardirq.h:11:
   In file included from arch/um/include/asm/hardirq.h:24:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:12:
   In file included from arch/um/include/asm/io.h:24:
   include/asm-generic/io.h:1209:55: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
   1209 |         return (port > MMIO_UPPER_LIMIT) ? NULL : PCI_IOBASE + port;
   |                                                   ~~~~~~~~~~ ^
   clang diag: include/asm-generic/io.h:1209:55: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
   clang diag: include/asm-generic/io.h:1209:55: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
   clang diag: include/asm-generic/io.h:1209:55: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
   1 warning generated.
>> error[E0599]: no method named `as_char_ptr` found for reference `&ffi::CStr` in the current scope
   --> rust/kernel/bug.rs:94:53
   |
   94 |                     $crate::c_str!(::core::file!()).as_char_ptr(),
   |                                                     ^^^^^^^^^^^
   |
   ::: rust/kernel/lib.rs:220:5
   |
   220 |     crate::bug!();
   |     ------------- in this macro invocation
   |
   = help: items from traits can only be used if the trait is in scope
   = note: this error originates in the macro `$crate::warn_flags` which comes from the expansion of the macro `crate::bug` (in Nightly builds, run with -Z macro-backtrace for more info)
   help: trait `CStrExt` which provides `as_char_ptr` is implemented but not in scope; perhaps you want to import it
   --> rust/kernel/lib.rs:35:1
   |
   35 + use crate::str::CStrExt;
   |

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